1. Field of the Invention
This invention relates to portable navigation devices and systems, and online navigation services in wireless communication systems. Specifically, this invention relates to portable communication devices such as cellular phones having navigation functions, navigation servers for providing online navigation services, and navigation systems for providing online navigation services as requested by portable communication devices connected with networks in wireless communications.
2. Description of the Related Art
Conventionally, so-called map information services are known as a typical example of navigation services, which are provided online via networks. That is, when the user who has a prescribed contract for receiving a certain navigation service operates a portable communication device such as a cellular phone to designate an item of ‘map’ on the screen, the prescribed server or service station sends corresponding map data to the portable communication device.
Recently, various types of navigation devices are developed and sold on the market. A typical example of the navigation device contains a GPS receiver (where ‘GPS’ stands for ‘Global Positioning System’) and provides communication functions via networks. Hence, the user of the navigation device is able to confirm his/her present position on the map that is downloaded thereto.
Japanese Unexamined Patent Publication No. Hei 7-91970 discloses a portable navigation device that contains a GPS device and an electronic compass, wherein the map displayed on the screen is rotated in such a way that its azimuth substantially matches the azimuth detected by the electronic compass. This publication discloses two types of processing for rotating the map on the screen. That is, the map is rotated on the screen by image processing, or the display is mechanically rotated by itself.
The conventional map information service does not provide indications of the destination and present position with respect to the portable communication device. Hence, the user of the portable communication device is unable to confirm his/her present position and destination on the map displayed on the screen. Therefore, it cannot be used as a guide or guidance for the user of the portable communication device.
The user of the navigation device having a communication function, which was actually sold on the market, may be able to confirm his/her present position and destination on the map displayed on the screen. However, the navigation device does not provide a function of notifying the user of his/her direction, i.e., azimuth thereof Therefore, the user should make some efforts to rotate the device with reference to an appropriate (land) mark and to establish an azimuth match.
In the above, the user would easily make a mistake in establishing an azimuth match, and it may take a long time for the user to determine the optimal path towards the destination. In addition, the conventional navigation devices may be difficult to operate and cause problems in manual operations for users of a certain age. Further, the conventional navigation devices require the users to change directions thereof and to establish azimuth matches prior to actual uses. Hence, it may be difficult for the users to properly hold the navigation devices and to view the screens.
The portable navigation device disclosed by the aforementioned publication requires complicated graphic processing, which may be expensive, in order to electronically ensure rotation of the map displayed on the screen by the prescribed image processing. In addition, it requires a complicated mechanism, which may be expensive, in order to ensure mechanical rotation of the display.